Three senators have proposed a resolution that will force the Senate to vote on US support for Saudi Arabia in the war in Yemen. The conflict has sparked the world’s largest humanitarian crisis, according to the UN.

Senators Bernie Sanders (I-Vermont), Mike Lee (R-Utah) and Chris Murphy (D-Connecticut) introduced a bipartisan joint resolution on Wednesday that calls for the removal of American armed forces in Yemen, the Middle East’s poorest country. Sanders emphasized the need for Congress to reclaim its constitutional prerogative.

“For far too long, Congress under the Democratic and Republican administrations has abdicated its constitutional role in authorizing war. The time is long overdue for Congress to reassert its constitutional authority,” Sanders said in a television address on Wednesday.

The resolution is part of a longstanding friction between Congress and the executive branch over military involvement overseas. It invokes the 1973 War Powers Resolution, which gives Congress the authority to overrule the president and withdraw the military if it deems the conflict is unauthorized.

The response from the Pentagon was swift and censorious. Acting general counsel William S. Castle sent Senate Majority Leader Mitch McConnell (R-Kentucky) a letter on Tuesday, opposing the resolution before it was even filed on Wednesday.

The letter says the resolution would undermine America’s ability to “build strong security architecture in the world,” and that US support for Saudi Arabia in Yemen does not fall under the remit of the War Powers Resolution because it does not constitute direct military action.

Yemen’s conflict pits the Zaidi Shiite rebel group, known as the Houthis, against a coalition of Sunni forces led by Saudi Arabia and forces loyal to former Saudi-backed president Abdu Rabbu Mansour Hadi, who was ousted in 2014 by the Houthis.

Former President Barack Obama’s administration began assisting the Saudi coalition in 2015. The US has backed the Saudi forces with intelligence, ammunition and refueling. The US is also a major supplier of arms to Saudi Arabia, the region’s richest country, and its allies in the conflict.

At least 10,000 Yemeni civilians have died and the country is experiencing a devastating famine and a cholera epidemic, according to Oxfam.

In November 2017, the House of Representatives passed a resolution declaring that US military assistance to Saudi Arabia in the Yemen conflict was not authorized. It did not prevent the US from providing support to Saudi Arabia, however.

The three congressmen who proposed the House resolution wrote an op-ed in the New York Times, stating: “We believe that the American people, if presented with the facts of this conflict, will oppose the use of their tax dollars to bomb and starve civilians.”

The Senate proposal was met with approval on Twitter.

Bernie Sanders and Mike Lee aligning to challenge Yemen policy is an example of genuine bipartisan cooperation, but won't get widely celebrated as such because it doesn't involve dropping bombs, shredding civil liberties, or cutting social services

A Washington crime and cover-up has triggered the world's worst humanitarian crisis. Call 1-833-786-7927 to tell your Senator to join @SenSanders & @SenMikeLee to end a secretive, unconstitutional U.S.-Saudi war in Yemen. Together, we can help save millions of lives. #StopTheWarpic.twitter.com/EPijIY4GDq